Corrosion has always been and is currently a significant problem in the petroleum industry because of the necessary replacement costs and downtime associated therewith. This problem is true of the internal metal surfaces of transport pipelines.
Crude oil pipelines, for example, transport the production from one oilfield to a refinery, different grades of crude from different sources, or different crudes to different refineries along a pipeline route.
Pipelines often carry crude oil, or refined products, that have small amounts of water present. Current crude oil pipeline specifications allow for the presence of up to 5,000 volume ppm of water which is beyond the saturation point at normal temperatures. Corrosion of the metal surfaces of the pipeline is caused by accumulations of water. This occurs in the lower sections of the pipe or in areas of sludge accumulation, where water will separate from the hydrocarbon. This water will often be found to contain impurities such as chloride salts of calcium, magnesium and sodium, as well as bicarbonate, lower carboxylate, bisulfide ions, and the like which can contribute to the metal corrosion.
In view of the foregoing, industry is looking for techniques and inhibitors to combat corrosion caused by water present in the hydrocarbon to alleviate problems with the transport of crude oils via pipeline.